1. Field of the Invention
This invention relates generally to releasable fasteners and more particularly to an explosive actuated release mechanism which is mechanically two fault tolerant for effecting release.
For aerospace applications, structural release devices must be extremely reliable particularly when required to operate in a potentially catastrophic event. It is desirable that the release device be able to sustain great loads, be adaptable to a variety of configuration and load requirements, and yet be of relatively light weight and size. It may also be important that the device transmit a very low impulse into adjacent structure upon its actuation and that there be no ejected pieces or debris following release.
2. Background Art
There have been many designs for releasable fasteners including explosively releasable fasteners. Most of these are mechanically zero fault tolerant since failure of a single component renders them inoperative. As an example, redundant pin pullers for release of a toggle have been employed in a releasable fastener. Clamps, such as a Marmon clamp assembly, have also been used which utilize two bolts for joining structures together wherein each bolt is severable by an independent pair of cutters. In such designs, however, failure of multiple components will not effect a release.
Releasable fasteners which employ a single explosive device for retracting or shearing a single latching member are shown in U.S. Pat. Nos. 3,024,592; 3,084,597; and 3,119,298. Other releasable fasteners, wherein a single explosive device is used to retract a plurality of latching members are shown in U.S. Pat. Nos. 2,489,984 and 3,071,404. In U.S. Pat. No. 2,779,283, a connector is shown for securing an aerial vehicle to a booster rocket wherein the rocket gases cause the retraction of a pair of latching pawls in effecting a release. None of these devices, however, are mechanically two fault tolerant for effecting release.